Fully rerun the archive process for partially completed form archives
Fully rerun the archive process for partially completed form archives

previously if it got as far as archiving the form but failed during the signals, say,
then it would leave a permanantly unprocessed UnfinishedArchiveStub in the queue,
because xform.archive does nothing if the form is already archived.

dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq